The present invention relates to an automatic flaw-cutting method and apparatus for wire-shaped metal which automatically and mechanically cuts flaws detected on the surface of coiled wire-shaped metals.
This invention also relates to a flaw-removal method and apparatus for wire-shaped metals having a deeper flaw than specified cutting allowance and more than two flaws located on the same sectional surface of wire-shaped metal.
Up to the present, the following methods for removing the flaws existing on the surface of wire-shaped metals such as bearing steel and stainless steel have been used:
(a) Peeling all surfaces of wire-shaped metals by applying chipping dies;
(b) Peeling all surfaces of wire-shaped metals by using a centerless peeling machine;
(c) Grinding the flawed portions by using a hand grinder after visually detecting the flaws;
(d) Grinding marked portions after detecting the flawed portions along the entire length of a wire-shaped metal by an automatic flaw-detecting device and marking the flawed portions with paint.
However, there are drawbacks which increase costs in methods like (a) and (b) above, such as yield rate dropping and early wearing of the peeling tool. And in methods (c) or (d), although they remarkably improve the yield rate of the product by peeling only the portions to be removed, they require unbinding of the wire-shaped metal, and visual detection of the flaws along the entire length and all peripheries, or visual detection of the paint-marked portion around the periphery. Consequently, these methods are difficult to work, inefficient and incur remarkably high labor costs.
The present invention was developed in consideration of the above-mentioned drawbacks, and its first object is to reduce labor costs, to increase produce yield rate, to shorten processing time, and to reduce production costs by automatically cutting only the flawed portions of a wire-shaped metal.
However, in order to remove harmful flaws entirely, the following problems must be resolved.
Namely, in a conventional automatic flaw cutting apparatus, a coiled wire-shaped metal is supported on a horizontal cannon-shaped wire supply stand, which wire-shaped metal is then supplied to an automatic flaw-cutting line.
By applying this method, the coil of the wire-shaped metal installed on the cannon-shaped supply stand is able to be drawn horizontally without rotation, and supplied into the flaw-cutting line.
Accordingly, it becomes possible to supply a new coil during a non-stop flaw-cutting process by installing another alternative coil supply stand in parallel with the working stand, by welding the end tip of the new coil supported on the alternative stand to the tip of the end turn of the running coiled wire-shaped metal while the flaw-removing process is performed.
However, when the cannon-shaped supply stand is used, since a wire-shaped metal is installed on the stand and placed horizontally, and introduced into the flaw-cutting line without rotation, the wire-shaped metal is twisted along its axis and the degree of twisting becomes indefinite. Due to this twisting, the peripheral positions of flaws detected by the flaw-detecting device do not coincide with the tooling position prepared in the flaw-cutting device. As a result, flawless portions might be cut while flawed portions remain.
In considering the above drawbacks, the second object of the present invention is to provide an automatic flaw-cutting method and apparatus enabling the peripheral position of the detected flaw to coincide with the tooling position prepared in the flaw-cutting device, by placing a twist-rectifying drum in front of the flaw-detecting device, and by winding the wire-shaped metal drawn from the cannon-shaped supply stand around the rectifying drum in a length longer than one turn of the coiled wire-shaped metal.
Further, the cutting allowance of the flaw-cutting device is specified so as to cut as much as the predetermined depth on the same periphery of the wire-shaped metal by using only one bite, in order to prevent the failure of the bite and disconnection of the wire-shaped metal during the flaw-cutting operation.
Accordingly, there is the possibility of leaving a flaw remaining if a flaw deeper than the specified cutting allowance exists. Further, if more than two flaws exist on the same peripheries of the wire-shaped metal, an uncut flaw will remain.
In consideration of the above-mentioned drawbacks, the third object of the present invention is to provide an automatic flaw-cutting method and apparatus enabling flaw cutting by hand when a non-cut flaw is detected, by installing a flaw-check and flaw-cutting site between a drawing die and a winding drum individually composing a wire-drawing apparatus, and by automatically stopping the wire-shaped metal on the way to the site when the non-cut flaw is found, and by removing the flaw by hand.